1. Field of the Invention
The present invention relates to a data transfer system for an electronic device that transfers information from a first function unit of an electronic device to a second function unit over a signal line. The invention also relates to a media processing device and to a control method for the media processing device.
2. Description of Related Art
As an example of an electronic device that uses a recording agent, inkjet printers can electrically detect the ink resistance, which changes according to the amount of remaining ink, by embedding an electrode in a sponge impregnated with water-based ink inside the ink cartridge and applying a voltage pulse to the electrode. While a main circuit board separate from the carriage detects the ink end using this voltage pulse, the same number of signal wires as colors of ink are needed to connect each of the ink end pins to the detector on the main circuit board. This results in many wire cores in the cable running between the main circuit board and the carriage. See, for example, Japanese Unexamined Patent Appl. Pub. JP-A-H06-246929.
A configuration such as this having a plurality of function units in a single electronic device thus connects the function units with the number of signal wires needed to carry the remaining ink status data to the second function unit. For example, if the printer uses six colors of ink, cyan, light cyan, light magenta, magenta, yellow, and black, and the remaining ink level is monitored in three levels, normal, near-end and real-end, two data bits are required to express these three remaining ink levels. Because there are six colors of ink, 2 bits×6 colors=12 bits, and 12 signal wires are therefore needed.
The data transfer method used in conventional electronic devices thus requires 12 signal wires to transfer the ink type (ink color) and ink level information from the first function unit to the second function unit, and this increases the system cost.